left to one's choice; not required or mandatory: Formal dress is optional.
leaving something to choice.

Origin of optional

First recorded in 1755–65; option + -al1
Related formsop·tion·al·i·ty, nounop·tion·al·ly, adverbnon·op·tion·al, adjectivenon·op·tion·al·ly, adverbun·op·tion·al, adjectiveun·op·tion·al·ly, adverb

Synonyms for optional

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for optional

Contemporary Examples of optional

Historical Examples of optional

  • The use of a Scripture lesson is, of course, optional with the pastor.

  • The manner of fastening the ribs to the frame pieces is optional.

    Flying Machines

    W.J. Jackman and Thos. H. Russell

  • Hence we erase all optional marks in the 1st and 3rd rows, but let them stand in the 2nd.

    A Tangled Tale

    Lewis Carroll

  • It never occurred to him that that duty was only optional with him now.

  • It is optional with the judges whether the use of a timepiece is to be allowed.

    Boy Scouts Handbook

    Boy Scouts of America

British Dictionary definitions for optional



possible but not compulsory; left to personal choice
Derived Formsoptionally, adverb
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for optional

1765, from option + -al (1).

Online Etymology Dictionary, © 2010 Douglas Harper